Whenever a gas company turns on the gas supply to a business or a residential customer, it is necessary to perform a number of checks to insure the integrity of the system. These tests are primarily used to verify utilization pressure, regulator lock-up and identify any leaks that may exist on the customer's piping. The utilization pressure is that pressure existing in the customer's piping during normal gas use. The regulator lock-up indicates the pressure existing in the line with minimal or no gas flow. Leaks, of course, must be eliminated except for those due to such things as pilot light orifices, etc.
In the past, utilization pressure and regulator lock-up have been tested by placing a valve and pressure gauge on the outlet to the gas meter and disconnecting the customer's piping from the gas meter. The company lock-stop valve to the meter was slowly opened, allowing gas to pass through the meter. With the lock-stop valve open, a calibrated valve adjacent the pressure gauge on the outlet of the gas meter is opened to allow approximately thirty cubic foot an hour of gas to flow therethrough. This flow of gas will open the regulator and the pressure can be noted on the pressure gauge. A set-point pressure of approximately four ounces indicates a correct setting on the indicator. If the set-point pressure is higher or lower, the regulator would then be adjusted.
After the regulator pressure was set properly, the calibrated valve was closed to prevent gas flow through the meter. The regulator will then shut the flow of gas off; a condition called lock-up. A slight increase in pressure from approximately one quarter of an ounce to one ounce may be noted above the set-point, as the regulator locks up. If the pressure rises above this, then the regulator has not locked up and it would be replaced.
When the leak test was performed in the past, it was necessary to utilize the actual gas meter to determine if there a leak was present. Typically, the gas meter was hooked up to the customer's piping and then the test hands on the face of the meter observed. Typically, the test hands measure volume in 1/4 foot, 1/2 foot, 1 foot, 2 foot, etc., increments. The technician typically observed the 1/4, 1/2 and 1 foot test hands for a period of approximately five minutes to determine if there had been any movement. Depending upon the local regulations for the shut-in test, a certain amount of movement will be tolerated. However, it can be appreciated that this prior leak testing method does require some type of calibration to the meter to insure that the test hands in fact move. To perform this test, a calibrated orifice is placed on the outlet to the meter and the orifice opened. This will result in a predetermined movement of the hands, thus insuring that the hands will provide an indication of low level gas flow. This is typically referred to as the "slow-fire" test. After the meter has been calibrated in this manner to assure that it operates at low gas flows, the meter would then be hooked up to the customer's piping and the hands on the face of the meter observed for any movement over a predetermined observation time.
The test procedures under present regulations and with present systems consume a considerable amount of time, as much as fifteen minutes per test. This can present a disadvantage since a flat fee is charged for a particular hook-up. Therefore, if the time for performing a given test can be reduced, significant increases in revenue can result due to the increase in efficiency. Further, present systems have some reliability problems in performing leak tests as they utilize the gas meter itself to indicate the existence of a leak. These procedures typically prove to be inadequate. Therefore, there exists a need for an improved testing system that both increases efficiency and eliminates calibration problems.